The invention relates to a pressure transducer for generating an electric signal that corresponds to a liquid pressure to be measured in a liquid container, with a measuring cell arranged in an external tube, which measuring cell can be partly filled with a liquid and the remainder with a gas, in which a line that can be filled up with the liquid leads away from the measuring cell, which line is open at the end facing away from the measuring cell and can be directly connected with the liquid in the liquid container; and in which means for generating an electric magnitude which corresponds to the gas volume in the measuring cell is arranged, as well as with an inner tube enclosed by an outer tube.
A pressure transducer of this type, which is a miniature pressure transducer, is known from the U.S. Pat. No. 3,942,382. In this pressure transducer, a thin capillary extends axially into the measuring cell and connects the inner tube, which serves for the supply of the transmission of fluid, with the line that can be filled with this fluid, which line can be directly connected to the liquid container, for example, a blood vessel. When the transducer is filled with transmission fluid, for example, with salt solution, then this fluid flows via the inner tube through the capillary and into the line which can be directly connected to the liquid container. Upon filling the pressure transducer with the transmission fluid, a meniscus between this fluid and the gas volume at the end of the capillary is supposed to be formed between the inner wall of the outer tube and the outer wall of the capillary. This meniscus must have a specific position in the measuring cell, so that impeccable measuring results can be attained. When the capillary which is supposed to extend axially into the measuring cell lying in the outer tube is somewhat bent or does not lie exactly axially, falsified measurement values can ensue. Because of the capillary, further, the pressure transducer is complicated in its construction.